Wales caretaker coach Rob Howley is considering calling up Cardiff Blues teenager Rhys Patchell for the defence of their Six Nations crown.

The 19-year-old fly-half has emerged as a contender after impressing for the Blues in recent weeks, producing man-of-the-match performances in their victories over the Dragons and Munster. And Howley, who will again take charge of the Welsh team in the absence of Warren Gatland, is weighing up whether to call up Patchell as a third No.10 behind Dan Bigger and James Hook.

Scarlets No.10 Rhys Priestland has been ruled out of the tournament with an Achilles injury and Howley excited about Patchell's potential to step into Wales' squad.

"Rhys is a young, developing player who is an option for us, but whether we pick two or three No.10s in the squad we will have to wait and see," Howley told Walesonline.

"What is in no doubt is that Rhys has taken his chance with the Blues and I am in constant communication with Phil Davies and Gareth Baber about his talents. His kicking and defensive game is good and he is also quick to make a break and challenge the line."

Biggar and Hook will battle it out to replace Priestland in the starting XV for Wales' opening Six Nations against Ireland on February 2. And Howley insists it will be a close call between the two with Hook set to shrug off a shoulder injury ready for the Millennium Stadium opener and Biggar continuing to show big improvements.

"We will miss Rhys but we feel we have some strength in Dan and James," said Howley. "There is good competition there because they are both hugely skilful players.

"Dan was one of the form players going into the autumn before his injury against Samoa and he has been playing well since. We have always talked about Dan's kicking game being effective but he has become more of a running threat now.

"He is creating a lot of opportunities for the team and himself and is putting together an all-round game. Dan just needs to take it onto another level now when he gets the opportunities with Wales.

"I have spoken to James over the last few days and we are hoping he will play some part in Perpignan's final Amlin Challenge Cup game. Failing that, he should be available the following week in the French domestic league the weekend before the Ireland opener."

Tight-head prop Adam Jones is set to be fit after missing Wales' autumn internationals with a knee injury while flanker Dan Lydiate is battling to be fit for the tournament opener.

"Any side in world rugby would miss the likes of Adam and Dan," said Howley. "Adam coming back is a huge boost for a team because he is one of the best tight-heads in world rugby.

"We have seen how effective he can be at scrum time over the last four weeks for the Ospreys and he will add to our potency to the Welsh scrum. Dan was man of the series in the Six Nations last year and that says it all.

"You can see what he gave us with his ball carrying ability and his dynamic defensive prowess."